|Publication number||US3555251 A|
|Publication date||Jan 12, 1971|
|Filing date||Dec 6, 1967|
|Priority date||Dec 6, 1967|
|Also published as||DE1812037A1|
|Publication number||US 3555251 A, US 3555251A, US-A-3555251, US3555251 A, US3555251A|
|Original Assignee||Honeywell Inc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (1), Non-Patent Citations (1), Referenced by (90), Classifications (14)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent [111 3555,25 1
 Inventor Gideon Shavlt OTHER REFERENCES Skokie, Brooks: Problems in programming Coutrol Computers Au- 1 PP -N 688,613 tomation, February 1963 pp. 78-82  Filed Dec. 6, 1967  patented Jam l2, 197] Examiner-Malcolm A. Morrison  Assignee Honeywell Inc. Assistant ExaminerFelix D. Gruber Minneapolis, Minn Attorneys-Lamont B. Koontz, Francis A. Sirr and Clyde C. a corporation of Delaware  OPIIMIZING SYSTEM FOR A PLURALITY OF TEMPERATURE CONDITIONING APPARATUSES 6 Claims, 2 Drawing Figs.
[ Cl 235/151 ABSTRACT: A control system for optimizing the operation of 235/l50.l. 340/|72-5 a plurality of electrical power operated temperature condi-  Int. Cl i i i 4 l G06! 15/46 timing apparatuses wherein a digit, compute.- periodically  Field of Search 235/ l S l determines the prevafling total temperature conditioning load,
1501' 15m; 236/14 155 340/1725 selects the number of apparatuses to be energized, and distributes the total load by using efficiency data stored in the  Referenm Cited computer for each apparatus to thereby operate each ap- UNITED STATES PATENTS paratus to supply a selected portion of the total at a minimum 3,309,507 3/ 1967 Schlein 235/ 1 50.1 total electrical power consumption for all the apparatuses.
r" r r r r r A r r r r 43 UNIT I CONTROL POWER 5| I, ,24 RELAY SENSOR 3' '3 22 l TEMP SENSOR 63 gCOMPRESSOR r i l UN|T I conosusm T AND I I 8EVAPORATOR 3 r L I5 341 64 TEMP i 36 52 CONTROLLER 33 l2 l l J' T0 \35 23 Q BUILDING 70 FLOW 52 FLOW 53 SENSOR SENSOR H I TO l3' m w r e s we UNIT UN IT 7 i I I T "Ln 1? DIGITAL o I3' I3'" K v f 3] COMPUTER 50 W 3T0 3' TEMP SENSOR l 1 To 42 4s 4? STORAGE ALARM PROGRAM SUPPLY WATER APPARATUS T APPARATUS TEMP CONTROL 45 PATENIEU JIII I 2 I971 FIG. 2
SHEET 2 (1F 2 STORED DATA (FOR ONE CHILL ER) COMPRESSOR HEAD 0R DIFFERENTIAL TEMPERATURE AT 5 #83? AT AT AT M4 AT AT ELECTRICAL ELECTRICAL ELECTRICAL ELECTRICAL ELECTRICAL 0 POWER POWER PowER PowER POWER v II T I T INVENTHR GIDEON SHAVIT ATTORNEY.
OPI'IMIZING SYSTEM FOR A PLURALITY OF TEMPERATURE CONDITIONING APPARA'I'USES BACKGROUND OF THE INVENTION With the advent of low cost digital computers, the supervision and control of power operated temperature conditioning apparatuses for large buildings by a digital computer has become economically practical. The desirability of optimizing the operation of temperature conditioning apparatus for the most economical operation has always been an aim of the building engineer. With the rapid change in factors such as outdoor temperature, wind, sun, radiation, as well as internal conditions such as the number of human beings, lighting heat, and the number of operating appliances, the total temperature conditioning load varies so rapidly that a human being is limited in his capability of maintaining the most efficient operation.
SUMMARY OF THE INVENTION The present invention is concerned with a control system for distributing a total temperature conditioning load among a plurality of power operated temperature conditioning apparatuses by using a digital computer to optimize the load distribution to the apparatuses in order to obtain a minimum power input for all operating apparatuses.
Specifically, the computer calculates the total temperature conditioning load of a building, determines and energizes the number of apparatuses needed for the calculated load, distributes the total load to the apparatuses in accordance with stored efficiency data for each apparatus for optimizing, and controls each apparatus to obtain the selected distribution. Additionally the computer updates stored efficiency data by measuring certain apparatus operating characteristics periodically, whereby on subsequent optimizing operations the upgraded data is used.
BRIEF DESCRIPTION OF THE DRAWING FIG. I is a schematic representation of a temperature conditioning system having four water chillers connected to supply chilled water to a building for air conditioning, with a digital computer for controlling the operation of the chillers, and FIG. 2 is a schematic showing of data stored in apparatus 46.
DESCRIPTION Referring to FIG. 1, a water temperature conditioning system delivers chilled medium or water by a supply pipe 11 and return pipe 12 to apparatus in a building, not shown, using chilled water for air cooling. System 10 comprises a plurality of temperature conditioning apparatuses or water chiller units 13, 13', 13" and 13".
All chillers are identical. Referring to chiller 13, each chiller has a condenser 14, a power source or motor 15 and a compressor and evaporator 20. Upon the energization of motor 15, from a source of power through a control relay 21, heat is removed from water entering the evaporator through pipe 22 to supply chilled water through pipe 23. The heat from the condenser is removed by a medium or water from a cooling tower 24 from which water is circulated by a pump 25 into the inlet pipe 30 of the condenser. The power or electrical energy to motor 15 is measured by an electrical power responsive apparatus or power sensor 31. The capacity of water chiller 13 is controlled by a temperature controller 32 having a remote temperature responsive element 33 responsive to the temperature of the water leaving the evaporator in pipe 23. The output 34 of temperature controller 32 is connected to control the capacity of the compressor in a conventional manner, such as by operating a suction damper to control the flow of refrigerant to the evaporator. The control point of temperature controller 32 is adjusted by means of an input 35. Chiller 13, as well as the other chillers, also have differential temperature signal apparatuses or AT sensors 36 and 37 which will be described in more detail.
The four water chillers are connected in a series-parallel relation whereby water from return pipe 12 is pumped by a pump 40 into the inlet of water chiller l3 and then through chiller 13' to be delivered to the supply pipe 11. Connected in series-parallel are chillers 13" and 13" with a pump 41 pumping water from return pipe 12 into series connected water chillers l3" and 13" to deliver chilled water to supply pipe 11.
A digital computer 42 has a plurality of inputs and a plurality of outputs which are connected to receive and deliver signals to the various elements of system 10. Computer 42 has a storage means or apparatus 46 which can store data and a program apparatus 47 for operating the water chillers in an efficient manner.
Stored in the storage means of the computer is initial data or tables of operating characteristics for each water chiller as shown schematically in FIG. 2. The initial data is obtained when the chiller is first operated or from the chiller manufacturer and is stored as in a matrix with refrigeration cooling load in tons (12,000 BTU/hr.) as one axis and differential temperature as the other axis, with a value of electrical power input for each combination of load and differential temperature. The differential temperature, which is one parameter indicative of compressor head, is the difference between the entering condenser water temperature and the leaving chiller water temperature.
OPERATION Assuming that the stored program of the digital computer 42 provides for the energization of at least one of the water chillers for an initial startup condition, control relay 21 is energized through output 43 and water chiller 13 is operated to remove heat from the water circulating through the evaporator. Upon the computer receiving a signal from a supply water temperature control apparatus 45, indicative of the desired temperature of the supply water, such as 46 F., to meet the cooling load of the building, the computer adjusts the control point of temperature controller 32 by means of output 35.
The temperature conditioning load of the building is calculated by the computer by responding to (I) the difference between the inlet and outlet water temperature as sensed by the temperature responsive elements 51 and 50 which are connected to the input of the computer, and (2) the combined water flow in each of the parallel branches as sensed by the flow responsive apparatus or sensors 52 and 53 which are connected to the input of the computer. Knowing the building temperature conditioning load (total tons of refrigeration cooling needed to satisfy the cooling requirement of the building) computer 42 controls the energimtion of the relays 21 of the water chillers so that the number of chillers energized is within the closest tons exceeding the building temperature conditioning load. Assuming that the temperature conditioning load was calculated as 1800 tons, computer 42 energizes the control relays 21 to start water chillers 13' and 13". With chillers 13, 13 and 13" operating, at a maximum output and assuming the chillers are 800 ton water chillers, a temperature conditioning capacity of 2400 tons could be obtained.
AT sensor 36 ha a temperature responsive element 55 in the inlet water pipe of the condenser and a temperature responsive element 60 in the outlet water pipe of the evaporator, whereby a differential temperature output signal indicative of compressor head from output 61 is connected to the input of the computer. Either assuming an arbitrary differential temperature signal if the now operating chiller was just energized, or using the differential temperature signal from apparatus 36 if the chiller has been operating, computer 42 refers to the stored initial data to distribute the total load to the three operating water chillers so a total electrical power consumption is as low as possible. Such a distribution might result in the three operating chillers having a selected load of 600, 500 and 700 tons for the respective chillers to make up the 1800 ton total load.
After the load which each chiller is to supply has been determined, the computer then adjusts the output of each operating chiller by adjusting the control point of the temperature controller 32 of each operating chiller. AT sensor 37 having a temperature responsive means 63 in the inlet pipe 22 and a temperature responsive means 64 in the outlet pipe 23 provides an output signal at 65 for each operating chiller which is connected to the input of the computer to be indicative of the temperature difference between the inlet and outlet water of the chiller. A flow signal is received from water flow sensor 52 by an output 70 connected to the input of the computer to provide a quantity flow measurement. The thermal output of each chiller can be calculated by (l) the differential temperature and (2) the quantity water flow. By the adjustment of the control point of controller 32 of chillers l3, l3 and 13' until the output of the respective chillers is at the selected level (500, 600 and 700 tons for the example), the total ton output is 1800 tons Computer 42 is programmed for an optimizing operation of system every minutes so that the number of chillers being operated and/or the readjustment of the chiller temperature controller is redetermined every 20 minutes to maintain optimum operation.
As the building load changes, the signal from apparatus 45 is used by the computer to readjust the supply water temperature as measured by element 50, by changing the control point of controller 32 of the operating chillers. Assuming that apparatus 45 signals for a need for 44" F. supply water, the computer readjusts controller 32 of the operating chillers until element 50 indicates 44 F. water temperature. The supply water temperature adjustment may take place several times inbetween the optimizing Operation.
The operating characteristics of the chillers can change as the total operating time of the chiller increases due to physical changes, such as when lime collects in the water pipes. At the end of each 20 minute period, before a new optimizing operation is made, the computer measures for each operating chiller the prevailing values of 1) electrical power input as measured by sensor 31 connected to input 71, (2) the tons of refrigeration output, and (3) the temperature difierential signal between the condenser inlet water and the evaporator outlet water which are utilized to update the stored data for each operating chiller. To obtain the updated value, 5 percent of the prevailing value of electrical power input is added to 95 percent of previously stored updated value of the electrical power input and a new updated value is stored in the computer along side the initial value for the particular tons-differential temperature combination. In this manner, the updating operation of the stored data takes place in the smooth manner to keep the stored data updated for subsequent optimizing operations. By means of a signal indication apparatus or alarm 72 connected to the output of the computer, when the updated value of power input exceeds the initial value of power for a particular chiller tons-differential temperature combination by some predetermined amount (such as l0 percent) an alarm is energized to acknowledge the fact that the operating characteristics of the water chiller have changed to an extent requiring possible overhaul or maintenance.
1. A control system for optimin'ng the distribution of a temperature conditioning load among a plurality of power operated temperature conditioning apparatuses by selectively distributing the load to the apparatuses to obtain a minimum total power input for operation of the apparatuses, comprising:
a computer having a plurality of inputs and outputs, storage means and program means; said storage means has stored therein data of temperature conditioning load levels and values of power input for various values of parameters of the apparatuses, said data being stored for each of the apparatuses whereby said program means can select the temperature conditioning load for each apparatus in accordance with said data to provide for the optimum combined power operation of the apparatuses;
first condition responsive means responsive to the total temperature conditioning load;
means connecting said first responsive means to one of said computer inputs whereby said computer receives a signal indicative of the total temperature conditioning load;
a plurality of second condition responsive means each being responsive to at least one parameter of each of said apparatuses;
means connecting each of said second responsive means individually to other of said computer inputs whereby said computer receives a signal indicative of an operating parameter of each apparatus;
said computer including said program means and said storage means distributing the total temperature conditioning load to said apparatuses using said parameter of each apparatus to load each apparatus at a particular power input to obtain the minimum total power input for the needed operation level of the apparatuses to provide said total temperature conditioning load;
controller means for each apparatus connected to its respective apparatus for controlling the operation thereof; and
means connecting said controller means of each apparatus individually to one of said outputs of said computer whereby said computer adjusts the operation of each apparatus to distribute the total temperature conditioning load to the apparatuses to provide a minimum total power input for all apparatuses.
2. The control system of claim 1 wherein said computer periodically updates said data stored in said storage means for each apparatus with prevailing data obtained during operation whereby updated data for each of the apparatuses is available including:
input power responsive means for each apparatus individually connected to an input of said computer, and wherein said second condition responsive means is responsive to a parameter indicative of compressor head.
3. The control system of claim 2:
wherein said storage means stores the initial value of input power and the updated value of input power for each combination of compressor head and output of each apparatus and including: indication means connected to said computer, said indication means being energized when said updated input power exceeds said initial input power by a predetermined amount.
4. The system of claim 2 wherein said computer upon updating said data uses a first percent of the last value of said data and a second percent of the prevailing value of said data.
5. The control system of claim I:
wherein each of said apparatuses are refrigeration water chillers having a compressor, medium cooled condenser and a water chilling evaporator;
said evaporators having water inlets and outlets combined to furnish chilled water to a building;
wherein said first condition responsive means comprises a difierential temperature responsive means responsive to the water temperature of the water supplied to the building and returning from the building and flow responsive means responsive to the total water flow to the building whereby the building temperature conditioning load is determined by said computer;
wherein said data for each water chiller includes a thermal output versus a differential temperature with an input power for said compressor for each combination of thermal output and differential temperature, said differential temperature being the difference between the temperature of the condenser inlet water and the evaporator outlet water whereby for a particular differential temperature said program means can select the thermal output of a chiller to provide the minimum input power;
water temperature for each chiller.
6. The control system of claim 1:
wherein said data is periodically updated for each apparatus as data is obtained; and
wherein each of said second responsive means is responsive to a parameter indicative of compressor head.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3309507 *||Jan 17, 1963||Mar 14, 1967||North American Aviation Inc||Optimal controller computer|
|1||*||Brooks: Problems in programming Coutrol Computers Automation, February 1963 pp. 78 82|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US3873817 *||May 4, 1972||Mar 25, 1975||Westinghouse Electric Corp||On-line monitoring of steam turbine performance|
|US3875384 *||Nov 6, 1973||Apr 1, 1975||Westinghouse Electric Corp||Protection system for transferring turbine and steam generator operation to a backup mode especially adapted for multiple computer electric power plant control systems|
|US3878401 *||Jun 10, 1974||Apr 15, 1975||Westinghouse Electric Corp||System and method for operating a turbine-powered electrical generating plant in a sequential mode|
|US3898441 *||Nov 6, 1973||Aug 5, 1975||Westinghouse Electric Corp||Multiple computer system for operating a power plant turbine with manual backup capability|
|US3911286 *||Sep 11, 1973||Oct 7, 1975||Westinghouse Electric Corp||System and method for operating a steam turbine with a control system having a turbine simulator|
|US3925645 *||Mar 7, 1975||Dec 9, 1975||Westinghouse Electric Corp||System and method for transferring between boiler-turbine plant control modes|
|US3934128 *||Oct 16, 1973||Jan 20, 1976||Westinghouse Electric Corporation||System and method for operating a steam turbine with improved organization of logic and other functions in a sampled data control|
|US3937934 *||Dec 21, 1973||Feb 10, 1976||Westinghouse Electric Corporation||System and method for operating a steam turbine with digital control having validity checked data link with higher level digital control|
|US3959635 *||Apr 26, 1972||May 25, 1976||Westinghouse Electric Corporation||System and method for operating a steam turbine with digital computer control having improved automatic startup control features|
|US4025765 *||Aug 10, 1973||May 24, 1977||Westinghouse Electric Corporation||System and method for operating a steam turbine with improved control information display|
|US4028532 *||Nov 2, 1973||Jun 7, 1977||Westinghouse Electric Corporation||Turbine speed controlling valve operation|
|US4029255 *||Oct 16, 1973||Jun 14, 1977||Westinghouse Electric Corporation||System for operating a steam turbine with bumpless digital megawatt and impulse pressure control loop switching|
|US4029951 *||Oct 21, 1975||Jun 14, 1977||Westinghouse Electric Corporation||Turbine power plant automatic control system|
|US4029952 *||Nov 6, 1973||Jun 14, 1977||Westinghouse Electric Corporation||Electric power plant having a multiple computer system for redundant control of turbine and steam generator operation|
|US4031372 *||Nov 6, 1973||Jun 21, 1977||Westinghouse Electric Corporation||System for manually or automatically transferring control between computers without power generation disturbance in an electric power plant or steam turbine operated by a multiple computer control system|
|US4035624 *||Oct 16, 1973||Jul 12, 1977||Westinghouse Electric Corporation||System for operating a steam turbine with improved speed channel failure detection|
|US4037088 *||Nov 6, 1973||Jul 19, 1977||Westinghouse Electric Corporation||Wide load range system for transferring turbine or plant operation between computers in a multiple computer turbine and power plant control system|
|US4053745 *||Nov 12, 1975||Oct 11, 1977||Westinghouse Electric Corporation||Valve contingency detection system for a turbine power plant|
|US4053746 *||Oct 17, 1973||Oct 11, 1977||Westinghouse Electric Corporation||System and method for operating a steam turbine with digital computer control having integrator limit|
|US4053747 *||Nov 6, 1973||Oct 11, 1977||Westinghouse Electric Corporation||System for initializing a backup computer in a multiple computer electric power plant and turbine control system to provide turbine and plant operation with reduced time for backup computer availability|
|US4057715 *||Nov 6, 1973||Nov 8, 1977||Westinghouse Electric Corporation||Wide range system for transferring steam generator and turbine operation between computers in a multiple turbine computer control system|
|US4088875 *||Nov 4, 1975||May 9, 1978||Westinghouse Electric Corp.||Optimum sequential valve position indication system for turbine power plant|
|US4090065 *||Oct 5, 1973||May 16, 1978||Westinghouse Electric Corp.||System and method for operating a steam turbine with protection provisions for a valve positioning contingency|
|US4123796 *||Nov 19, 1976||Oct 31, 1978||Powers Regulator Company||Controller for environmental conditioning apparatus|
|US4200911 *||Oct 20, 1977||Apr 29, 1980||Hitachi, Ltd.||Control of the flow rate and fluid pressure in a pipeline network for optimum distribution of the fluid to consumers|
|US4205380 *||Aug 10, 1973||May 27, 1980||Westinghouse Electric Corp.||System and method for operating a steam turbine with digital computer control with accelerating setpoint change|
|US4210957 *||May 8, 1978||Jul 1, 1980||Honeywell Inc.||Operating optimization for plural parallel connected chillers|
|US4213174 *||May 31, 1977||Jul 15, 1980||Andover Controls Corporation||Programmable sequence controller with drum emulation and improved power-down power-up circuitry|
|US4213182 *||Dec 6, 1978||Jul 15, 1980||General Electric Company||Programmable energy load controller system and methods|
|US4234926 *||Dec 5, 1978||Nov 18, 1980||Sealand Service Inc.||System & method for monitoring & diagnosing faults in environmentally controlled containers, such system and method being especially adapted for remote computer controlled monitoring of numerous transportable containers over existing on-site power wiring|
|US4274145 *||Dec 31, 1979||Jun 16, 1981||Microcomm Corporation||Digital thermostat|
|US4316256 *||Dec 31, 1979||Feb 16, 1982||Microcomm Corporation||Thermostat with automatic heat/air conditioning changeover|
|US4328556 *||Apr 16, 1979||May 4, 1982||Tokyo Denryoku Kabushiki Kaisha||Control system of plants by means of electronic computers|
|US4354241 *||Dec 27, 1979||Oct 12, 1982||Butler Manufacturing Company||Programmable electronic real-time load controller providing for adaptation of load control in response to varying environmental conditions|
|US4418285 *||Dec 30, 1977||Nov 29, 1983||Westinghouse Electric Corp.||System and method for controlling a turbine power plant in the single and sequential valve modes with valve dynamic function generation|
|US4431134 *||Nov 8, 1982||Feb 14, 1984||Microcomm Corporation||Digital thermostat with protection against power interruption|
|US4445180 *||Nov 6, 1973||Apr 24, 1984||Westinghouse Electric Corp.||Plant unit master control for fossil fired boiler implemented with a digital computer|
|US4483152 *||Jul 18, 1983||Nov 20, 1984||Butler Manufacturing Company||Multiple chiller control method|
|US4510576 *||Jul 26, 1982||Apr 9, 1985||Honeywell Inc.||Specific coefficient of performance measuring device|
|US4511895 *||Nov 24, 1981||Apr 16, 1985||General Electric Company||Method and apparatus for controlling distributed electrical loads|
|US4655277 *||Apr 27, 1984||Apr 7, 1987||Phillips Petroleum Company||Process control for parallel heat exchangers|
|US4687946 *||Apr 26, 1972||Aug 18, 1987||Westinghouse Electric Corp.||System and method for operating a steam turbine with digital computer control and with improved monitoring|
|US4726893 *||May 16, 1986||Feb 23, 1988||Phillips Petroleum Company||Catalytic crackins process control|
|US4739926 *||May 4, 1987||Apr 26, 1988||Eckardt Ag||Process for the control of at least two process entities|
|US4747912 *||Aug 24, 1987||May 31, 1988||Phillips Petroleum Company||Cracking furnace control|
|US4852362 *||Jul 16, 1985||Aug 1, 1989||Multistack, Inc.||Modular refrigeration system|
|US4967712 *||Dec 4, 1989||Nov 6, 1990||Injection Research Specialists, Inc.||Two-cycle engine with electronic fuel injection|
|US5276630 *||Jul 23, 1990||Jan 4, 1994||American Standard Inc.||Self configuring controller|
|US5291607 *||Oct 23, 1992||Mar 1, 1994||Motorola, Inc.||Microprocessor having environmental sensing capability|
|US5621654 *||Apr 15, 1994||Apr 15, 1997||Long Island Lighting Company||System and method for economic dispatching of electrical power|
|US7082380 *||Nov 21, 2003||Jul 25, 2006||David Wiebe||Refrigeration monitor|
|US7680834||Jun 8, 2004||Mar 16, 2010||Bakbone Software, Inc.||Method and system for no downtime resychronization for real-time, continuous data protection|
|US7689602||Jul 20, 2005||Mar 30, 2010||Bakbone Software, Inc.||Method of creating hierarchical indices for a distributed object system|
|US7788521||Jul 20, 2005||Aug 31, 2010||Bakbone Software, Inc.||Method and system for virtual on-demand recovery for real-time, continuous data protection|
|US7904913||Nov 1, 2005||Mar 8, 2011||Bakbone Software, Inc.||Management interface for a system that provides automated, real-time, continuous data protection|
|US7979404||Sep 17, 2004||Jul 12, 2011||Quest Software, Inc.||Extracting data changes and storing data history to allow for instantaneous access to and reconstruction of any point-in-time data|
|US7979441||Jan 21, 2010||Jul 12, 2011||Quest Software, Inc.||Method of creating hierarchical indices for a distributed object system|
|US8060889||Nov 15, 2011||Quest Software, Inc.||Method and system for real-time event journaling to provide enterprise data services|
|US8108429||May 6, 2005||Jan 31, 2012||Quest Software, Inc.||System for moving real-time data events across a plurality of devices in a network for simultaneous data protection, replication, and access services|
|US8131723||Mar 31, 2008||Mar 6, 2012||Quest Software, Inc.||Recovering a file system to any point-in-time in the past with guaranteed structure, content consistency and integrity|
|US8151140||Jul 28, 2010||Apr 3, 2012||Quest Software, Inc.||Method and system for virtual on-demand recovery for real-time, continuous data protection|
|US8195628||Oct 11, 2010||Jun 5, 2012||Quest Software, Inc.||Method and system for data reduction|
|US8200706||Jul 11, 2011||Jun 12, 2012||Quest Software, Inc.||Method of creating hierarchical indices for a distributed object system|
|US8352523||Sep 23, 2011||Jan 8, 2013||Quest Software, Inc.||Recovering a file system to any point-in-time in the past with guaranteed structure, content consistency and integrity|
|US8364648||Apr 9, 2008||Jan 29, 2013||Quest Software, Inc.||Recovering a database to any point-in-time in the past with guaranteed data consistency|
|US8365017||Jan 29, 2013||Quest Software, Inc.||Method and system for virtual on-demand recovery|
|US8375248||Feb 12, 2013||Quest Software, Inc.||Method and system for virtual on-demand recovery|
|US8429198||Jun 6, 2012||Apr 23, 2013||Quest Software, Inc.||Method of creating hierarchical indices for a distributed object system|
|US8453469 *||Jun 29, 2011||Jun 4, 2013||Exaflop Llc||Changing data center cooling modes|
|US8544023||Oct 11, 2010||Sep 24, 2013||Dell Software Inc.||Management interface for a system that provides automated, real-time, continuous data protection|
|US8639974||Dec 20, 2012||Jan 28, 2014||Dell Software Inc.||Method and system for virtual on-demand recovery|
|US8650167||Jun 1, 2012||Feb 11, 2014||Dell Software Inc.||Method and system for data reduction|
|US8712970||Jan 28, 2013||Apr 29, 2014||Dell Software Inc.||Recovering a database to any point-in-time in the past with guaranteed data consistency|
|US8972347||Dec 14, 2012||Mar 3, 2015||Dell Software Inc.||Recovering a file system to any point-in-time in the past with guaranteed structure, content consistency and integrity|
|US9113582 *||May 17, 2010||Aug 18, 2015||Fujitsu Limited||Air conditioning control apparatus and air conditioning control method|
|US20040210419 *||Nov 21, 2003||Oct 21, 2004||David Wiebe||Refrigeration monitor|
|US20050262097 *||May 6, 2005||Nov 24, 2005||Sim-Tang Siew Y||System for moving real-time data events across a plurality of devices in a network for simultaneous data protection, replication, and access services|
|US20060101384 *||Nov 1, 2005||May 11, 2006||Sim-Tang Siew Y||Management interface for a system that provides automated, real-time, continuous data protection|
|US20070153478 *||Jan 2, 2007||Jul 5, 2007||Lite-On Technology Corporation||Method for controlling fan rotational speed in electronic system and electronic system applying the same|
|US20080179416 *||Dec 3, 2007||Jul 31, 2008||Johnson David E||Modulation control of a hydronic heating system|
|US20090314484 *||Dec 24, 2009||Akz Technologies Llc||Standalone flow rate controller for controlling flow rate of cooling or heating fluid through a heat exchanger|
|US20100298997 *||May 17, 2010||Nov 25, 2010||Fujitsu Limited||Air conditioning control apparatus and air conditioning control method|
|US20110011080 *||Jun 19, 2009||Jan 20, 2011||Panasonic Corporation||Refrigeration cycle apparatus|
|US20120130560 *||May 24, 2012||Lsis Co., Ltd.||Temperature control module and temperature control apparatus having the same|
|US20140069120 *||Sep 4, 2013||Mar 13, 2014||Mitsubishi Heavy Industries, Ltd.||Control apparatus and method for parallel-type chiller, and computer-readable recording medium in which program for parallel-type chiller is stored|
|US20140202177 *||Nov 4, 2013||Jul 24, 2014||Charles Warrener Rush||Cooling water process control system|
|EP2697577A2 *||Mar 20, 2012||Feb 19, 2014||Trane International Inc.||Water flow measurement device|
|EP2697577A4 *||Mar 20, 2012||Sep 24, 2014||Trane Int Inc||Water flow measurement device|
|WO1991009359A1 *||Dec 12, 1989||Jun 27, 1991||Injection Research Specialists||Two-cycle engine with electronic fuel injection|
|WO2012141852A2||Mar 20, 2012||Oct 18, 2012||Trane International Inc.||Water flow measurement device|
|U.S. Classification||700/286, 700/299, 165/287, 236/DIG.800|
|International Classification||F24F11/00, G05D23/20|
|Cooperative Classification||F24F11/0012, G05D23/2015, F24F11/00, Y10S236/08, F24F2221/56, F24F2011/0061|
|European Classification||G05D23/20D, F24F11/00|